The man on the verge of taking over the New York Stock Exchange isn’t happy with the way its running.

The Wall Street Journal reports that Jeffrey Sprecher, chief executive of IntercontinentalExchange (ICE), said on Tuesday that U.S. exchanges were “not fair” to individual investors and “fundamentally wrong.” He was speaking on an investor call.

Sprecher took aim at high-speed traders, who exploit technological advantages to access market information and execute trades milliseconds ahead of their lower-tech competitors. He characterized this trading method as “not particularly warranted or helpful or sustainable,” and proposed a fundamental rethink of the way exchanges work.

Meanwhile, shares in ICE climbed 2.1 percent on Tuesday, as executives predicted a deal with the NYSE would close within days. For high-speed traders, the clock could be ticking in a new and unsettling way.